The overhead traveling vehicle transports cassettes such as semiconductor cassettes or reticle cassettes in a clean room or the like. A pair of safety covers are provided on front and rear sides of a body of an overhead traveling vehicle in a traveling direction for preventing fall of transported articles such as the cassettes. Further, the overhead traveling vehicle has a safety frame facing a lid of the cassette for preventing fall of the article due to detachment of the lid from the cassette. Further, a photoelectric sensor is provided in the frame to detect detachment of the lid (Japanese Patent Publication No. 2004-277066). For added safety against lid detachment, in the case where a lid has been detached from a cassette, e.g., at a load port, it is necessary to detect detachment of the lid also at the time of elevating the casette by an elevation unit.